Schmaltz was acquired by the Coyotes in a trade with the Chicago Blackhawks for forwards Brendan Perlini and Dylan Strome on Nov. 25, 2018.
Selected by Chicago with the No. 20 pick in the 2014 NHL Draft, Schmaltz has 105 points (34 goals, 71 assists) in 179 regular-season games.
"Nick is a highly skilled, creative, young center with extremely high upside," Arizona general manager John Chayka said. "Getting Nick signed to a long-term extension is another positive step towards building a sustainable contender here in the Valley. Ownership continues to commit the resources necessary to solidify our core group of players for years to come."
The Coyotes (37-33-8) are three points behind the Colorado Avalanche for the second wild card into the Stanley Cup Playoffs from the Western Conference. They host the Minnesota Wild on Sunday (5 p.m. ET; FS-A Plus; FS-WI, FS-N+, ESPN+, NHL.TV).